Camera and optical apparatus

ABSTRACT

A camera capable of stabilizing the open state and closed state of barrier blades is disclosed. The camera comprises a lens barrel which holds a lens; and a barrier unit placed closer to the end of the lens barrel than a flange which is formed on the lens barrel and extends in the direction orthogonal to the optical axis, wherein the barrier unit has: a barrier member which opens/closes the front of the lens through a rotation operation; a barrier driving mechanism which drives the barrier member according to the operation of the lens barrel; and a partition plate which separates the barrier member from the barrier driving mechanism in the direction of the optical axis, and a shaft which supports the barrier member in a rotatable manner is formed on the flange.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a camera provided with a open/closetype barrier mechanism which protects the lens front of a lens barreland an optical apparatus.

2. Description of the Related Art

There are proposals of various types of a barrier mechanism which isprovided in front of an image-pickup lens of a camera and causes barrierblades to perform an open/close operation in conjunction with operations(protruding and retracting) of the lens barrel in the direction of theoptical axis. A basic structure of the barrier mechanism is shown inFIG. 4.

Two barrier blades 101 are supported by rotation shafts 102 in arotatable manner through engagement of hole portions 101 a with therotation shafts 102. The rotation shafts 102 are provided on a baseplate (not shown) (e.g., lens barrel, etc.). Then, driving pins 101 bengage with notch portions 103 a of a first driving ring 103.

The first driving ring 103 engages with a second driving ring 104 in arotatable manner and is energized by an absorption spring 105 withrespect to the second driving ring 104 in the direction indicated byarrow A (one turn direction). Here, since a hooking shaft 103 b normallycontacts a stopper 104 a of the second driving ring 104 by spring forceof the spring 105, the first driving ring 103 normally operates togetherwith the second driving ring 104 as one unit.

The second driving ring 104 is held by a base plate (not shown) (e.g.,lens barrel, etc.) in a rotatable manner and energized by an openingspring 106 in the direction indicated by arrow B.

One end of the opening spring 106 is fixed to a hooking shaft 107 andthe hooking shaft 107 is provided on a base plate (not shown) (e.g.,lens barrel, etc.). The first driving ring 103 and second driving ring104 are rotated by the opening spring 106 in the direction indicated byarrow B and cause the barrier blades 101 to rotate in the openingdirection (direction indicated by arrow C) as a result. Since thebarrier mechanism is held by a base plate (not shown) (e.g., lensbarrel, etc.), the barrier blades 101 are in an open state when the lensbarrel protrudes and it is an image-pickup state. On the other hand,when the lens barrel retracts and it is in a non-image-pickup state, acam face 104 b of the second driving ring 104 contacts a cam-shapedprotrusion 108 inside the camera and moves along the cam-shapedprotrusion 108 and thereby causes the first driving ring 103 and seconddriving ring 104 to rotate in the direction indicated by arrow A. Inthis way, the barrier blades 101 rotate in the direction opposite to thedirection indicated by arrow C to close the lens front.

When an external force in the direction indicated by arrow C is appliedto the barrier blades 101 which are in a closed state, only the firstdriving ring 103 rotates in the direction indicated by arrow B againstthe spring force of the absorption spring 105.

In the above described structure, the structure in which the base plateand lens barrel house and hold the barrier mechanism will be explainedusing the cross-sectional views shown in FIG. 5 to FIG. 7. In thesefigures, the same members as those explained in FIG. 4 are assigned thesame reference numerals.

In the structure shown in FIG. 5 (first conventional example), asdisclosed in Japanese Patent Application Laid-Open No. H8 (1996)-234292and Japanese Patent Application Laid-Open No. H10 (1998)-186453, therotation shaft 102 and hooking shaft 107 (not shown) are directlyprovided in the lens barrel 109. Furthermore, the barrier mechanism ishoused in the lens barrel 109 and a barrier cover 110 covers the frontof the lens barrel 109.

The structure shown in FIG. 5 is simple and allows the barrier mechanismto be assembled from the front of the lens barrel 109.

The structure shown in FIG. 6 (second conventional example), as isdisclosed in Japanese Patent Application Laid-Open No. H9 (1997)-211536(corresponding to U.S. Pat. No. 5,862,426 and EP 0 788 020 A1), isconstructed in such a way that the barrier driving mechanism other thanthe barrier blade 101 is assembled from the inner side (right side inFIG. 6) of the lens barrel 109. In this structure, a plate 112 is usedto house the first driving ring 103 and second driving ring 104 withinthe lens barrel 109.

The structure shown in FIG. 7 (third conventional example) is astructure in which the barrier blades 101 and barrier driving mechanismare separated by a barrier base plate 113. Thus, the rotation shaft 102is provided on a barrier base plate 113.

However, in the structure shown in FIG. 5, when the barrier blades 101moves to the closing position, the second driving ring 104 may be pushedforward (left side in FIG. 5) in the lens barrel 109 by the cam-shapedprotrusion 108, thereby preventing the movement of the barrier blades101 and producing insufficient closing of the barrier blades 101.

On the other hand, in the structure shown in FIG. 6, since the part ofthe lens barrel 109 is located between the barrier blades 101 andbarrier driving mechanism (especially, second driving ring 104) otherthan the barrier blades 101, even if the second driving ring 104 ispushed forward in the lens barrel 109 by the cam-shaped protrusion 108as described above, the second driving ring 104 does not prevent themovement of the barrier blades 101.

However, since the barrier driving mechanism needs to be assembled fromthe inner side of the lens barrel 109 (right side in FIG. 6), it isdifficult to imbed the barrier mechanism in the lens barrel 109.

In the structure shown in FIG. 7, since the barrier base plate 113 isplaced between the barrier blades 101 and barrier driving mechanism(especially, the second driving ring 104), even if the second drivingring 104 is pushed in by the cam-shaped protrusion 108 as describedabove, the movement of the barrier blades 101 is not blocked. Moreover,the barrier mechanism can be assembled from the front side (left side inFIG. 7) of the lens barrel 109, and therefore it is also easy to imbedthe barrier mechanism in the lens barrel 109.

However, the structure shown in FIG. 7 may make the open state andclosed state of the barrier blades 101 unstable.

That is, the closed state and open state of the barrier blades 101 areaffected by the relative positional relationship between the rotationshaft 102 and driving pin 101 b, but if the rotation shaft 102 isprovided on the barrier base plate 113, the barrier base plate 113 moveswithin the plane orthogonal to the optical axis due to backlash ofengagement between the lens barrel 109 and barrier base plate 113,assembly error, part variations, etc., also causing the position of therotation shaft 102 to change.

Thus, when the position of the rotation shaft 102 changes, the relativepositional relationship between the rotation shaft 102 and driving pin101 b is not constant and the opening position and the closing positionof the barrier blades 101 are not fixed to a predetermined position, andtherefore the open state and the closed state of the barrier blades 101become unstable.

SUMMARY OF THE INVENTION

One aspect of a camera of the present invention comprises a lens barrelwhich holds a lens and a barrier unit placed closer to the end of thelens barrel than a flange which is formed on the lens barrel and extendsin the direction orthogonal to the optical axis. Here, the barrier unithas a barrier member which opens/closes the front of the lens through arotation operation, a barrier driving mechanism which drives the barriermember according to the operation of the lens barrel and a partitionplate which separates the barrier member from the barrier drivingmechanism in the direction of the optical axis, wherein a shaft whichsupports the barrier member in a rotatable manner is formed on theflange. One aspect of an optical apparatus of the present inventioncomprises a lens and a lens barrel which holds the lens. Here, the lensbarrel has ,in order from an object side, a barrier member which rotatesaround a first shaft and opens/closes the front of the lens, a partitionplate and a barrier driving member which drives the barrier memberthrough a second shaft, and the first shaft is united with the lensbarrel.

The features of the camera and optical apparatus of the invention willbecome more apparent from the following detailed description of apreferred embodiment of the invention with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a barrier mechanism accordingto an embodiment of the present invention;

FIG. 2 is a partial cross-sectional view of a lens barrel according tothe embodiment;

FIG. 3 is an external perspective view of a camera which is theembodiment;

FIG. 4(A) is an exploded perspective view of a conventional barriermechanism viewed from the front and FIG. 4(B) is an exploded perspectiveview viewed from the back;

FIG. 5 is a partial cross-sectional view of the conventional lensbarrel;

FIG. 6 is a partial cross-sectional view of the conventional lensbarrel; and

FIG. 7 is a partial cross-sectional view of the conventional lensbarrel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 and FIG. 2 show a barrier mechanism of a camera which is anembodiment of the present invention. FIG. 1 is an exploded perspectiveview of the barrier mechanism and FIG. 2 is a partial cross-sectionalview of a lens barrel provided with the barrier mechanism. FIG. 3 is anexternal perspective view (schematic view) of the camera.

In FIG. 3, reference numeral 21 denotes a camera body which containsvarious members necessary for image taking. Reference numeral 22 denotesa release button. An image-taking preparation operation (photometricoperation or focusing operation, etc.) is started by a half-depressingoperation of the release button 22 and an image-taking operation(exposure to a film or an image-pickup element such as CCD, etc.) isstarted by a full-depressing operation of the release button 22.

Reference numeral 23 denotes a view finder unit for observing an objectimage and 24 denotes a light projection unit which projects AF filllight, etc. Reference numeral 25 denotes an electronic flash unit whichirradiates an object with illumination light.

Reference numeral 26 denotes a lens barrel which holds an image-takinglens and can move (can protrude/retract) between a collapse state inwhich it is housed in the camera body 21 and an image-taking state inwhich it protrudes from the camera body 21. On the front of the lensbarrel 26, a barrier mechanism which will be described later isprovided.

Then, the structure of the barrier mechanism of this embodiment will beexplained using FIG. 1 and FIG. 2.

Hole portions 1 a are formed at the one end of the barrier blades(barrier member) 1. The barrier blades 1 are supported by rotationshafts 2 a in a rotatable manner by allowing the hole portions 1 a toengage with the rotation shafts 2 a provided in a holding member 2 (partof the lens barrel 26). Furthermore, driving pins 1 b are provided atpositions closer to the optical axis than the hole portions 1 a on thebarrier blades 1 and engage with notch portions 3 a of a first drivingring 3.

The first driving ring 3 engages with a second driving ring 4 in arotatable manner. An absorption spring 5 energizes the first drivingring 3 with respect to the second driving ring 4 in the directionindicated by arrow A with one end of the absorption spring 5 engagingwith a hooking shaft 3 c of the first driving ring 3 and the other endengaging with a hooking shaft 4 c of the second driving ring 4.

Here, by matching the phases of notch portions 3 b formed in three partsin the circumferential direction of the first driving ring 3 and thephases of protrusions 4 b formed in three parts in the circumferentialdirection of the second driving ring 4, it is possible to assemble thefirst driving ring 3 into the second driving ring 4.

At this time, the first driving ring 3 is energized in the directionindicated by arrow A by the spring 5, the end of the notch portions 3 bare pressed against the end of the protrusions 4 b, and therefore thefirst driving ring 3 and second driving ring 4 operate together as oneunit except when an opening/closing operation of the barrier blades 1 isperformed by external force as will be described later.

The second driving ring 4 is held by a lens holding portion 2 b of theholding member 2 in a rotatable manner. An opening spring 6 energizesthe second driving ring 4 in the direction indicated by arrow B with oneend of the opening spring 6 engaging with a hooking shaft 4 d of thesecond driving ring 4 and the other end engaging with the hooking shaft2 c of the holding member 2.

The first driving ring 3, second driving ring 4, absorption spring 5 andopening spring 6 are housed and held in the holding member 2 by beingpressed by a barrier base plate (partition plate) 7 from the front ofthe lens barrel 26 (right side in FIG. 2).

Here, the barrier base plate 7 is fixed by bayonet lugs 2 d provided inthe holding member 2. That is, in order to assemble the barrier baseplate 7 into the holding member 2, the barrier base plate 7 is attachedto the holding member 2 by matching the phases of the bayonet lugs 2 dand the phases of notch portions 7 a provided in the barrier base plate7 first and then the barrier base plate 7 is fixed to the holding member2 by rotating the barrier base plate 7 clockwise (direction indicated byarrow A).

At this time, the rotation shafts 2 a of the holding member 2 penetratethrough hole portions (recess portion) 7 b formed in the barrier baseplate 7 and support the barrier blades 1 in a rotatable manner. It isalso possible to form notch portions (recess portion) obtained bynotching the perimeter of the barrier base plate 7 instead of throughhole portions 7 b.

Furthermore, the barrier base plate 7 is provided with escape holeportions 7 c so that the driving pins 1 b of the barrier blades 1 canengage with the notch portions 3 a of the first driving ring 3. Theseescape hole portions 7 c is formed like an elongated hole and secure anmoving space of the driving pins 1 b in a rotation operation of thebarrier blades 1.

As the procedure for actually assembling the barrier mechanism into theholding member 2, the second driving ring 4, opening spring 6,absorption spring 5 and first driving ring 3 are assembled into theholding member 2 sequentially and then the barrier base plate 7 isassembled into the holding member. Then, the barrier blades 1 areassembled and covered with the barrier cover 8.

Elastic lugs 8 a are formed in the barrier cover 8 and the barrier cover8 is fixed to the holding member 2 with the elastic lugs 8 a engagingwith the holding member 2. At this time, the elastic lugs 8 a engagewith rotation stopper notch portions 7 d formed on the perimeter of thebarrier base plate 7.

Furthermore, protrusions 8 b provided on the rear face of the barriercover 8 engage with notch portions 2 e provided in the front of theholding member 2. This represses the barrier cover 8 from coming off theholding member 2 and also represses it from rotating around the opticalaxis. Then, the barrier cover 8 is fixed to the holding member 2, whichrepresses the barrier base plate 7 from rotating around the opticalaxis.

In this embodiment, as shown in FIG. 2, the barrier mechanism is locatedcloser to the end of the holding member 2 (left side in FIG. 2) than anend 2 f formed on the inner surface of the holding member 2, andtherefore it is possible to incorporate the barrier mechanism from thefront of the holding member 2. This makes it possible to easily assemblethe barrier mechanism (lens barrel).

Here, the end 2 f is formed at an proximal position with respect to thebarrier blades 1 in the lens barrel 26 and extends to the inner side ofthe holding member 2, that is, extends toward the image-taking opticalaxis. Furthermore, the end 2 f has a plane orthogonal to the opticalaxis.

In the above described structure, the barrier mechanism incorporatedfrom the front of the lens barrel 26 moves together with the holdingmember 2 as one unit according to the protruding/retracting operation ofthe lens barrel 26 in the direction of the optical axis.

When the lens barrel 26 protrudes and is in an image-taking state, thebarrier blades 1 are withdrawn from an opening 8 c formed in the centerof the barrier cover 8 and then remain open state. This allows a lightflux from an object to go into the lens barrel 26.

On the other hand, when the lens barrel 26 retracts from theimage-taking state into a collapse state, a cam face 4 a of the seconddriving ring 4 contacts a cam-shaped protrusion 9 provided in the camerabody 21 according to the retracting operation of the lens barrel 26.Then, the second driving ring 4 rotates in the direction indicated byarrow A (direction opposite to the direction indicated by arrow B)against the spring force of the opening spring 6 through the engagementbetween the cam face 4 a and cam-shaped protrusion 9.

When the second driving ring 4 rotates in the direction indicated byarrow A, the first driving ring 3 rotates in the direction indicated byarrow A by receiving the spring force of the absorption spring 5, thebarrier blades 1 rotate around the rotation shaft 2 a through theengagement between the notch portions 3 a and driving pins 1 b andcovers the opening 8 c.

When the lens barrel 26 protrudes from a collapse state into animage-taking state, the engagement between the cam face 4 a andcam-shaped protrusion 9 is released according to the protrudingoperation of the lens barrel 26. At this time, the second driving ring 4rotates in the direction indicated by arrow B by receiving the springforce of the opening spring 6 and the first driving ring 3 rotates inthe direction indicated by arrow B (direction opposite to the directionindicated by arrow A).

When the first driving ring 3 rotates in the direction indicated byarrow B, the barrier blades 1 rotate around the rotation shafts 2 athrough the engagement between the notch portions 3 a and driving pins 1b and withdraw from the opening 8 c into an open state.

When the barrier blades 1 are in a closed state, if an external force isapplied to the barrier blades 1 in the opening direction of the barrierblades 1, only the first driving ring 3 rotates in the directionindicated by arrow B against the spring force of the absorption spring5.

As shown in FIG. 2, in this embodiment, it is possible to incorporatethe barrier mechanism from the front of the lens barrel 26 and therebyeasily assemble the barrier mechanism.

Furthermore, since the barrier blades 1 and barrier driving mechanismhaving the second driving ring 4, opening spring 6, absorption spring 5and the first driving ring 3, are placed sandwiching the barrier baseplate 7, even if the second driving ring 4 (cam face 4 a) contacts thecam-shaped protrusion 9 and is pushed in to the front side of the lensbarrel 26, the movement (especially the closing operation) of thebarrier blades 1 is not blocked.

That is, since the displacements of the barrier base plate 7 and thebarrier cover 8 in the direction of the optical axis are repressed, thespace for the movement of the barrier blades 1 is secured.

Furthermore, in this embodiment, the rotation shafts 2 a are fixed tothe holding member 2, and therefore even if the barrier base plate 7moves within the plane orthogonal to the optical axis with respect tothe holding member 2 for reasons such as engagement backlash, assemblyerrors or parts variations, etc., the positions of the rotation shaftsare never shifted and the open state and closed state of the barrierblades 1 never become unstable.

In this embodiment, the hole portions 1 a are formed in the barrierblades 1 and the rotation shafts 2 a are formed in the holding member 2to cause the hole portions 1 a to engage with the rotation shafts 2 a,but the reverse structure may also be used. That is, it is also possibleto form rotation shafts in the barrier blades 1 and form hole portionswhich engage with the above described rotation shafts in the holdingmember 2.

Furthermore, in this embodiment, the barrier blades 1 are driven usingthe barrier driving mechanism having the first driving ring 3, seconddriving ring 4, absorption spring 5 and opening spring 6, but anystructure may be used if it is at least the structure which causes thebarrier blades 1 to move between the open position and the closedposition. In this case, the barrier driving mechanism is separated fromthe barrier blades by the barrier base plate 7 and the rotation shaftsof the barrier blades is provided in the lens barrel. Therefore, it ispossible to achieve the same purpose as this embodiment.

While preferred embodiment has been described, it is to be understoodthat modification and variation of the present invention may be madewithout departing from scope of the following claims.

1. A camera comprising: a lens barrel which holds a lens; and a barrierunit placed closer to the end of the lens barrel than a flange which isformed on the lens barrel and extends in the direction orthogonal to theoptical axis, wherein the barrier unit has: a barrier member whichopens/closes the front of the lens through a rotation operation; abarrier driving mechanism which drives the barrier member according tothe operation of the lens barrel; and a partition plate which separatesthe barrier member from the barrier driving mechanism in the directionof the optical axis, and a shaft which supports the barrier member in arotatable manner is formed on the flange.
 2. The camera according toclaim 1, wherein the partition plate has a recess portion to avoidinterfering with the shaft.
 3. The camera according to claim 1, whereinthe shaft and the flange are integrated with the lens barrel.